Method of applying protective coatings to metallic articles.



, C. MARK.

METHOD OF APPLYING PROTECTIVE COATINGS T0 METALLIC ARTICLES.

APPLICATION FILED IULY29. 1915.

1 1 84, 1 94. I Patented May 23 191 awpewfoz E STATES CLARENCE MARK, or EVANSTON, ILLINOIS, ASSIGNOB T CLAYTON MARK, or

' CHICAGO, ILLINOIS.

METHOB 0F APPLYING PROTECTIVE COATINGS TO METALLIC ARTICLES.

To all whom; it may concern Be it known that I, CLARENCE MARK, a citizen of the United States, residing at Evanston, in the county of Cook, State of Illinois, have invented a new and Improved such as are described and claimed in the co-pending application of Clarence Mark and Clayton Mark, Jr., Serial Number 841,484, filed May 28, 1914, which has become Patent No. 1,155,317, and consists in introducing the article to be coated into a bath containing lead and zinc having superimposed thereon a layerof zinc at the point at which the article is introducedinto the bath; I have found that lead alone, or lead and tin, or lead and antimony, will not adhere readily to iron or steel when low percentages of tin or antimony are used. Zinc, however, by its affinity for iron, readily unites with the iron and the resultant zinc-iron alloy formsa suitable base for adhesion of a leadtin-zinc or lead-zinc-antimony alloy. I therefore, in order to insure the formation of an adequate zinc-iron alloy on the surfaces of the article, superimpose a layer of zinc upon a portion of the alloy bath so 40 that when the article has first been passed through the zinc the alloy adheres very readily to it, and the resulting product is a very eflicient one. 1

Referring to the drawings, in -which I have shown apparatus of a character suitable for carrying out my invention,- A indicates a galvanizing pot or kettle, which contains amolten bath preferably composed of lead, tin andzinc, in approximately the following percentages: lead .87, zinc 3, tin 10.

At one end: of the receptacle A is a container B, open at top and bottom, which confines the molten'zinc and separates it from the remainder of the kettle. The zinc,

as it "is lighter than the alloy of lead, tin

Specification of Letters Patent.

Patented May 23, 1916.

Application filed July 29, 1915. Serial No. 42,577.

apld zinc, is supported and floats upon the a 0 Y The articles to be treated, which'I have shown in the form of pipes D, are first introduced into the zinc container B, and are pushed-down through the zinc bath, and the underlying alloy bath, to the bottom of the kettle by a submerging implement C. In passing the articles through the zinc the articles will acquire enough zinc toform a zinc-iron alloy on their surfaces. They are held on the bottom until they have reached the temperature of the bath so that any unv alloyed zinc will be freed therefrom, and will rise up into the container B. The submerging implement C is then tilted (as is shown in full lines in Fig. l) to permit the articles D, because of their lighter specific gravity, to rise to the surface .of the bath, outside of. the container. They are then removed, .and allowed to cool,'and when cooled are found to have a uniform, closely adhering coating, superimposed upon the zinc-iron alloy.

In application ,Serial No. 841,484, which has become Patent No. 1,155,317, referred to above, a method of periodically replenishing the zinc in the bath was described and claimed. In carrying out the present process I have found that the articles will carry down suflicient zinc into the bath to keep up the desired content of zinc, so that separate additions of zinc are not required.

In Fig. 2 I have shown a type of appa-. ratus suitable for carrying out a modification of my process, and which isparticw. larly adapted to the treatment of articles mechanically introduced" into and carried out of the bath in a rapid and continuous manner. .To prevent too much zinc from being carried along through. and out of the bath by the articles, I prefer to'pre-heat the articles and to this end'I have shown a kettle E, which may be filled with lead, orsome other metal, suitable for use in pre-heating the container B, and down into and up out v ofthe bath A. Because of the high temperature at which the articles enter the zinc bath, a comparatively small proportion of unalloyed zinc will adhere to the article,

, and so an excess of zinc will not be carried down into the alloy bath and the resulting article willaccordlngly not have an excess of unalloyed zinc upon its surfaces.

The terms and expressions, WhichIhave employed are used as terms of description and not of limitation, and I have no intention in the use of such terms and expressions of excluding any equivalent for the features shownand described, but recognize that various modifications may bemade within the scope of the invention claimed.

What I claim is: 1. The herein described method of applying protective coatings to metallic articles, which consists of passing the article .tobe coated through a molten bath containing lead and zinc, the bath having superimposed upon it, at the point of hntrance of.

of the article, a layer of molten zinc, whereby the zinc forms with the article a zinciron alloy, thereb providing a base of adhesion for the a loy containing lead and zinc.

ing protective coatings to metallic articles, which consists in pre-heatlng the article by passing the same through a molten bath 7' I and then subsequently passing the article through a second molten bath containing "2. The herein described process of apply lead and zinc, the bath at the point of entrance of the article being covered with alayer of zinc, whereby the zinc forms a zinc-iron alloy on the article, therebyproviding a base of adhesion for the alloy containing lead and'zinc,

' CLARENCE MARK. 

